SC-FDMA系统中的资源分配算法

发布时间：2018-09-06 10:00

【摘要】：单载波频分多址(single carrier frequency division multiple access, SC-FDMA)因具有较低的功率峰均比(peak to average power ratio,PAPR)而受到广泛的关注,并被第三代合作伙伴计划的长期演进(Third Generation Partnership Project-Long Term Evolution,3GPP-LTE)和LTE-Advanced标准采纳为上行多址方案。在该系统中采用灵活的资源分配可以进一步提高系统容量。但局部映射式SC-FDMA系统的子信道相邻限制,即每个用户只能被分配相邻的多个子信道,增加了SC-FDMA系统资源分配最优方案的求解难度。本文提出了一种局部映射式SC-FDMA系统中的增强型贪婪资源分配算法。基站首先根据信道相干带宽划分子频带,选取在子频带上具有较大正比公平权重的用户,为他们确定子信道的起始位置。然后考虑局部映射式SC-FDMA的子信道相邻限制,以最大化正比公平权重和的增量为目标,把剩余子信道逐个分配给用户。基于3GPP-LTE上行方案的仿真结果表明,与传统贪婪算法相比,增强型贪婪算法能提高系统的频谱利用率,同时提升用户间的公平性,其性能非常接近最优算法,并具有较低的计算复杂度。另一方面,协作中继能为系统提供空间分集增益,降低无线信道衰落对传输可靠性的影响,改善系统性能。中继协助的SC-FDMA系统能克服频率选择性衰落、阴影损耗等影响,增加可达的系统吞吐量,保证用户的通信质量。本文还研究了适用于SC-FDMA中继系统中最大化容量的资源分配算法,提出将该资源分配问题重构为一个集合划分问题。借鉴集合划分问题在运筹学中的相关算法,可以求解出该资源分配的最优解。为降低最优资源分配算法的计算复杂度,本文还提出了一种基于贪婪试探策略的次优算法。基于3GPP-LTE上行方案的仿真结果表明,在放大转发和解码转发中继协助的SC-FDMA系统中,最优算法的频谱利用率显著高于随机算法,而贪婪次优算法能达到接近最优算法的性能,并且具有较低的计算复杂度。
[Abstract]:Single carrier frequency division multiple access (single carrier frequency division multiple access, SC-FDMA) has attracted much attention due to its low PAPR (peak to average power ratio,PAPR), and has been adopted as an uplink multiple access scheme by the (Third Generation Partnership Project-Long Term Evolution,3GPP-LTE and LTE-Advanced standards of the third Generation Partnership. Flexible resource allocation in the system can further improve the system capacity. However, the subchannel adjacent limitation of the local mapping SC-FDMA system is that each user can only be allocated several adjacent subchannels, which makes it more difficult to solve the optimal resource allocation scheme of SC-FDMA system. This paper presents an enhanced greedy resource allocation algorithm for locally mapped SC-FDMA systems. The base station first divides the sub-band according to the channel coherent bandwidth and selects the users with a large proportional fair weight on the sub-band to determine the starting position of the sub-channel for them. Then, considering the adjacent subchannel constraints of the local mapping SC-FDMA, the residual subchannels are assigned to the users one by one, aiming at maximizing the increment of the proportional fair weight sum. The simulation results based on 3GPP-LTE uplink scheme show that compared with the traditional greedy algorithm, the enhanced greedy algorithm can improve the spectrum efficiency of the system and the fairness between users, and its performance is very close to the optimal algorithm. And it has low computational complexity. On the other hand, cooperative relay can provide spatial diversity gain for the system, reduce the influence of wireless channel fading on transmission reliability, and improve the system performance. The relaying assisted SC-FDMA system can overcome the influence of frequency selective fading, shadow loss and so on, increase the throughput of reachable system and guarantee the communication quality of users. This paper also studies the resource allocation algorithm suitable for maximizing capacity in SC-FDMA relay system, and proposes to reconstruct the resource allocation problem into a set partition problem. The optimal solution of the resource allocation can be obtained by using the relevant algorithms of the set partition problem in operations research. In order to reduce the computational complexity of the optimal resource allocation algorithm, a suboptimal algorithm based on greedy heuristic strategy is proposed. The simulation results based on 3GPP-LTE uplink scheme show that the spectrum efficiency of the optimal algorithm is significantly higher than that of the random algorithm in the SC-FDMA system assisted by amplifying and decoding forwarding relays, while the greedy sub-optimal algorithm can achieve the performance close to the optimal algorithm. And it has low computational complexity.
【学位授予单位】：复旦大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN929.5

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